Method and apparatus for distracting a joint

ABSTRACT

A joint-spacing balloon catheter comprising:
         a shaft having a distal end and a proximal end;   first and second balloons mounted to the distal end of the shaft, the first balloon being disposed distal to, and spaced from, the second balloon, with the portion of the shaft between the first and second balloons being flexible; and   a handle attached to the proximal end of the shaft.

REFERENCE TO PENDING PRIOR PATENT APPLICATIONS

This patent application:

(i) is a continuation-in-part of pending prior U.S. patent applicationSer. No. 12/726,268, filed Mar. 17, 2010 by Julian Nikolchev et al. forMETHOD AND APPARATUS FOR DISTRACTING A JOINT, INCLUDING THE PROVISIONAND USE OF A NOVEL JOINT-SPACING BALLOON CATHETER AND A NOVEL INFLATABLEPERINEAL POST (Attorney's Docket No. FIAN-28424953), which claimsbenefit of: (a) prior U.S. Provisional Patent Application Ser. No.61/210,315, filed Mar. 17, 2009 by Julian Nikolchev et al. for JOINTSPACING BALLOON CATHETER (Attorney's Docket No. FIAN-28 PROV); (b) priorU.S. Provisional Patent Application Ser. No. 61/268,340, filed Jun. 11,2009 by Julian Nikolchev et al. for METHOD AND APPARATUS FOR DISTRACTINGA JOINT, INCLUDING THE PROVISION AND USE OF A NOVEL JOINT-SPACINGBALLOON CATHETER AND A NOVEL INFLATABLE PERINEAL POST (Attorney's DocketNo. FIAN-42 PROV); (c) prior U.S. Provisional Patent Application Ser.No. 61/278,744, filed Oct. 9, 2009 by Julian Nikolchev et al. for METHODAND APPARATUS FOR DISTRACTING A JOINT, INCLUDING THE PROVISION AND USEOF A NOVEL JOINT-SPACING BALLOON CATHETER AND A NOVEL INFLATABLEPERINEAL POST (Attorney's Docket No. FIAN-49 PROV); and (d) prior U.S.Provisional Patent Application Ser. No. 61/336,284, filed Jan. 20, 2010by Julian Nikolchev et al. for METHOD AND APPARATUS FOR DISTRACTING AJOINT, INCLUDING THE PROVISION AND USE OF A NOVEL JOINT-SPACING BALLOONCATHETER AND A NOVEL INFLATABLE PERINEAL POST (Attorney's Docket No.FIAN-53 PROV);

(ii) claims benefit of pending prior U.S. Provisional Patent ApplicationSer. No. 61/411,179, filed Nov. 8, 2010 by William Kaiser et al. forMETHOD AND APPARATUS FOR DISTRACTING A JOINT, INCLUDING THE PROVISIONAND USE OF A NOVEL JOINT-SPACING BALLOON CATHETER AND A NOVEL INFLATABLEPERINEAL POST (Attorney's Docket No. FIAN-68 PROV);

(iii) claims benefit of pending prior U.S. Provisional PatentApplication Ser. No. 61/452,477, filed Mar. 14, 2011 by Hal David Martinet al. for METHOD AND APPARATUS FOR DISTRACTING A JOINT, INCLUDING THEPROVISION AND USE OF A NOVEL JOINT-SPACING BALLOON CATHETER AND A NOVELINFLATABLE PERINEAL POST (Attorney's Docket No. FIAN-72 PROV); and

(iv) claims benefit of pending prior U.S. Provisional Patent ApplicationSer. No. 61/492,640, filed Jun. 2, 2011 by William Kaiser et al. forMETHOD AND APPARATUS FOR DISTRACTING A JOINT, INCLUDING THE PROVISIONAND USE OF A NOVEL JOINT-SPACING BALLOON CATHETER AND A NOVEL INFLATABLEPERINEAL POST (Attorney's Docket No. FIAN-75 PROV).

The eight (8) above-identified patent applications are herebyincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to surgical methods and apparatus in general, andmore particularly to surgical methods and apparatus for treating a hipjoint.

BACKGROUND OF THE INVENTION The Hip Joint in General

The hip joint is a ball-and-socket joint which movably connects the legto the torso. The hip joint is capable of a wide range of differentmotions, e.g., flexion and extension, abduction and adduction, medialand lateral rotation, etc. See FIGS. 1A, 1B, 1C and 1D.

With the possible exception of the shoulder joint, the hip joint isperhaps the most mobile joint in the body. Significantly, and unlike theshoulder joint, the hip joint carries substantial weight loads duringmost of the day, in both static (e.g., standing and sitting) and dynamic(e.g., walking and running) conditions.

The hip joint is susceptible to a number of different pathologies. Thesepathologies can have both congenital and injury-related origins. In somecases, the pathology can be substantial at the outset. In other cases,the pathology may be minor at the outset but, if left untreated, mayworsen over time. More particularly, in many cases, an existingpathology may be exacerbated by the dynamic nature of the hip joint andthe substantial weight loads imposed on the hip joint.

The pathology may, either initially or thereafter, significantlyinterfere with patient comfort and lifestyle. In some cases, thepathology can be so severe as to require partial or total hipreplacement. A number of procedures have been developed for treating hippathologies short of partial or total hip replacement, but theseprocedures are generally limited in scope due to the significantdifficulties associated with treating the hip joint.

A better understanding of various hip joint pathologies, and also thecurrent limitations associated with their treatment, can be gained froma more thorough understanding of the anatomy of the hip joint.

Anatomy of the Hip Joint

The hip joint is formed at the junction of the leg and the hip. Moreparticularly, and looking now at FIG. 2, the head of the femur isreceived in the acetabular cup of the hip, with a plurality of ligamentsand other soft tissue serving to hold the bones in articulatingcondition.

More particularly, and looking now at FIG. 3, the femur is generallycharacterized by an elongated body terminating, at its top end, in anangled neck which supports a hemispherical head (also sometimes referredto as “the ball”). As seen in FIGS. 3 and 4, a large projection known asthe greater trochanter protrudes laterally and posteriorly from theelongated body adjacent to the neck of the femur. A second, somewhatsmaller projection known as the lesser trochanter protrudes medially andposteriorly from the elongated body adjacent to the neck. Anintertrochanteric crest (FIGS. 3 and 4) extends along the periphery ofthe femur, between the greater trochanter and the lesser trochanter.

Looking next at FIG. 5, the hip socket is made up of three constituentbones: the ilium, the ischium and the pubis. These three bones cooperatewith one another (they typically ossify into a single “hip bone”structure by the age of 25 or so) in order to collectively form theacetabular cup. The acetabular cup receives the head of the femur.

Both the head of the femur and the acetabular cup are covered with alayer of articular cartilage which protects the underlying bone andfacilitates motion. See FIG. 6.

Various ligaments and soft tissue serve to hold the ball of the femur inplace within the acetabular cup. More particularly, and looking now atFIGS. 7 and 8, the ligamentum teres extends between the ball of thefemur and the base of the acetabular cup. As seen in FIGS. 8 and 9, alabrum is disposed about the perimeter of the acetabular cup. The labrumserves to increase the depth of the acetabular cup and effectivelyestablishes a suction seal between the ball of the femur and the rim ofthe acetabular cup, thereby helping to hold the head of the femur in theacetabular cup. In addition to the foregoing, and looking now at FIG.10, a fibrous capsule extends between the neck of the femur and the rimof the acetabular cup, effectively sealing off the ball-and-socketmembers of the hip joint from the remainder of the body. The foregoingstructures (i.e., the ligamentum teres, the labrum and the fibrouscapsule) are encompassed and reinforced by a set of three main ligaments(i.e., the iliofemoral ligament, the ischiofemoral ligament and thepubofemoral ligament) which extend between the femur and the perimeterof the hip socket. See, for example, FIGS. 11 and 12, which show theiliofemoral ligament, with FIG. 11 being an anterior view and FIG. 12being a posterior view.

Pathologies of the Hip Joint

As noted above, the hip joint is susceptible to a number of differentpathologies. These pathologies can have both congenital andinjury-related origins.

By way of example but not limitation, one important type of congenitalpathology of the hip joint involves impingement between the neck of thefemur and the rim of the acetabular cup. In some cases, and looking nowat FIG. 13, this impingement can occur due to irregularities in thegeometry of the femur. This type of impingement is sometimes referred toas cam-type femoroacetabular impingement (i.e., cam-type FAI). In othercases, and looking now at FIG. 14, the impingement can occur due toirregularities in the geometry of the acetabular cup. This latter typeof impingement is sometimes referred to as pincer-type femoroacetabularimpingement (i.e., pincer-type FAI). Impingement can result in a reducedrange of motion, substantial pain and, in some cases, significantdeterioration of the hip joint.

By way of further example but not limitation, another important type ofcongenital pathology of the hip joint involves defects in the articularsurface of the ball and/or the articular surface of the acetabular cup.Defects of this type sometimes start out fairly small but often increasein size over time, generally due to the dynamic nature of the hip jointand also due to the weight-bearing nature of the hip joint. Articulardefects can result in substantial pain, induce and/or exacerbatearthritic conditions and, in some cases, cause significant deteriorationof the hip joint.

By way of further example but not limitation, one important type ofinjury-related pathology of the hip joint involves trauma to the labrum.More particularly, in many cases, an accident or sports-related injurycan result in the labrum being torn away from the rim of the acetabularcup, typically with a tear running through the body of the labrum. SeeFIG. 15. These types of injuries can be very painful for the patientand, if left untreated, can lead to substantial deterioration of the hipjoint.

The General Trend Toward Treating Joint Pathologies UsingMinimally-Invasive, and Earlier, Interventions

The current trend in orthopedic surgery is to treat joint pathologiesusing minimally-invasive techniques. Such minimally-invasive, “keyhole”surgeries generally offer numerous advantages over traditional, “open”surgeries, including reduced trauma to tissue, less pain for thepatient, faster recuperation times, etc.

By way of example but not limitation, it is common to re-attachligaments in the shoulder joint using minimally-invasive, “keyhole”techniques which do not require laying open the capsule of the shoulderjoint. By way of further example but not limitation, it is common torepair torn meniscal cartilage in the knee joint, and/or to replaceruptured ACL ligaments in the knee joint, using minimally-invasivetechniques.

While such minimally-invasive approaches can require additional trainingon the part of the surgeon, such procedures generally offer substantialadvantages for the patient and have now become the standard of care formany shoulder joint and knee joint pathologies.

In addition to the foregoing, in view of the inherent advantages andwidespread availability of minimally-invasive approaches for treatingpathologies of the shoulder joint and knee joint, the current trend isto provide such treatment much earlier in the lifecycle of thepathology, so as to address patient pain as soon as possible and so asto minimize any exacerbation of the pathology itself. This is in markedcontrast to traditional surgical practices, which have generallydictated postponing surgical procedures as long as possible so as tospare the patient from the substantial trauma generally associated withinvasive surgery.

Treatment for Pathologies of the Hip Joint

Unfortunately, minimally-invasive treatments for pathologies of the hipjoint have lagged far behind minimally-invasive treatments forpathologies of the shoulder joint and the knee joint. This is generallydue to (i) the constrained geometry of the hip joint itself, and (ii)the nature and location of the pathologies which must typically beaddressed in the hip joint.

More particularly, the hip joint is generally considered to be a “tight”joint, in the sense that there is relatively little room to maneuverwithin the confines of the joint itself. This is in marked contrast tothe shoulder joint and the knee joint, which are generally considered tobe relatively “spacious” joints (at least when compared to the hipjoint). As a result, it is relatively difficult for surgeons to performminimally-invasive procedures on the hip joint.

Furthermore, the pathways for entering the interior of the hip joint(i.e., the natural pathways which exist between adjacent bones and/ordelicate neurovascular structures) are generally much more constrainingfor the hip joint than for the shoulder joint or the knee joint. Thislimited access further complicates effectively performingminimally-invasive procedures on the hip joint.

In addition to the foregoing, the nature and location of the pathologiesof the hip joint also complicate performing minimally-invasiveprocedures on the hip joint. By way of example but not limitation,consider a typical detachment of the labrum in the hip joint. In thissituation, instruments must generally be introduced into the joint spaceusing an angle of approach which is offset from the angle at which theinstrument addresses the tissue. This makes drilling into bone, forexample, significantly more complicated than where the angle of approachis effectively aligned with the angle at which the instrument addressesthe tissue, such as is frequently the case in the shoulder joint.Furthermore, the working space within the hip joint is typicallyextremely limited, further complicating repairs where the angle ofapproach is not aligned with the angle at which the instrument addressesthe tissue.

As a result of the foregoing, minimally-invasive hip joint proceduresare still relatively difficult to perform and relatively uncommon inpractice. Consequently, patients are typically forced to manage theirhip pain for as long as possible, until a resurfacing procedure or apartial or total hip replacement procedure can no longer be avoided.These procedures are generally then performed as a highly-invasive, openprocedure, with all of the disadvantages associated withhighly-invasive, open procedures.

As a result, there is, in general, a pressing need for improved methodsand apparatus for treating pathologies of the hip joint.

Current Approaches for Hip Joint Distraction

During arthroscopic hip surgery, it is common to distract the hip jointso as to provide increased workspace within the joint. Moreparticularly, during arthroscopic hip surgery, it is common to unseatthe ball of the femur from the socket of the acetabular cup so as toprovide (i) improved access to the interior of the joint, (ii)additional workspace within the interior of the joint, and (iii)increased visibility for the surgeon during the procedure. This hipjoint distraction is normally accomplished in the same manner that thehip joint is distracted during a total hip replacement procedure, e.g.,by applying an external distraction device to the lower end of thepatient's leg near the ankle and then using the external distractiondevice to pull the leg distally with substantial force so as to unseatthe ball of the femur from the acetabular cup.

However, since the distracting force is applied to the lower end of thepatient's leg, this approach necessitates that the distracting force beapplied across substantially the entire length of the leg. As a result,the intervening tissue (i.e., the tissue located between where thedistracting force is applied and the ball of the femur) must bear thedistracting load for the entire time that the hip joint is distracted.

In practice, it has been found that the longer the distracting load ismaintained on the leg, the greater the trauma imposed on the interveningtissue. Specifically, it has been found that temporary or even permanentneurological damage can occur if the leg is distracted for too longusing conventional distraction techniques.

As a result, the standard of care in the field is for the surgeon tolimit the duration of distraction during arthroscopic hip surgery to 90minutes or less in order to minimize damage to the intervening tissuedue to joint distraction. In some situations, this can mean thatdesirable therapeutic procedures may be curtailed, or even eliminatedentirely, in order to keep the duration of the distraction to 90 minutesor less. And even where the duration of the distraction is kept to 90minutes or less, significant complications can nonetheless occur formany patients.

In addition to the foregoing, in current hip distraction, it is commonto use a perineal post to facilitate hip distraction. More particularly,and looking now at FIG. 16, a perineal post is generally positionedbetween the legs of the patient so that the medial side of the femurwhich is to be distracted lies against the perineal post. After thepatient's leg is pulled distally (i.e., in the direction of the pullingvector V_(P)), the leg is adducted so as to lever the leg against theperineal post, which moves the neck and ball of the femur in thedirection of the lateral vector V_(L); the combination of these twodisplacements is V_(D) (i.e., the resultant vector of the vectors ofV_(L) and V_(P)). This ensures that the ball of the femur is unseatedfrom the acetabular cup in the desired direction (i.e., in the directionof the resultant vector V_(D)).

Unfortunately, it has been found that the use of a perineal post cancontribute to the damage done to the intervening tissue when the leg isdistracted too long. This is because the perineal post can press againstthe pudendal nerve and/or the sciatic nerve (as well as other anatomy)when such distraction occurs. Thus, if the distraction is held too long,neurological damage can occur. This is another reason that the standardof care in the field is for the surgeon to limit the duration ofdistraction during arthroscopic hip surgery to 90 minutes or less.Additionally, the perineal post can exert pressure on the blood vesselsin the leg, and it has been shown that blood flow in these vessels(e.g., the femoral vein, etc.) may be significantly reduced, or in somecases completely occluded, while the hip is in distraction, thus placingthe patient in danger of forming deep vein thrombosis or developingother complications.

Additionally, current hip distraction using an external distractiondevice limits the extent to which the leg can be manipulated underdistraction during hip arthroscopy, since a substantial pulling forcemust be maintained on the distal end of the leg throughout the durationof the distraction. Due to this, and due to the fact that there aretypically only 2-4 portals available for surgical access into theinterior of the hip joint, visualization and access to hip jointpathology and anatomy is frequently hindered while the leg is beingexternally distracted. This can limit the extent of surgical proceduresavailable to the surgeon, and can prevent some procedures from beingattempted altogether. Procedures such as mosaicplasty and autologouscartilage injection are examples of procedures which require access toextensive areas of the articular surfaces of the femoral head, but whichare typically not performed arthroscopically because of theaforementioned access limitations when the leg is being distracted usingan external distraction device.

Thus, there is a need for a new and improved approach for distractingthe hip joint which addresses the foregoing problems.

SUMMARY OF THE INVENTION

These and other objects of the present invention are addressed by theprovision and use of a new method and apparatus for distracting a joint.

Among other things, the present invention provides a novel method fordistracting a joint and for maintaining distraction of a joint, whereinthe novel method minimizes damage to intervening tissue whilemaintaining distraction of the joint. In addition, the novel methodallows visualization of areas in the hip joint that were not previouslyvisible using a conventional hip distraction approach.

The present invention also provides novel apparatus for distracting ajoint and for maintaining distraction of a joint, wherein the novelapparatus comprises a novel joint-spacing balloon catheter formaintaining the distraction of a joint.

In one preferred form of the invention, there is provided a method forcreating space in a joint formed at the convergence of two bones, themethod comprising:

applying force to a body part so as to separate the two bones from oneanother by a distance which is greater than the distance that they arenormally separated from one another when the joint is in a healthystate, whereby to distract the joint and create an intrajoint space;

inserting at least one balloon into the intrajoint space while the atleast one balloon is in a contracted condition;

expanding the at least one balloon within the intrajoint space; and

reducing the force applied to the body part so that the joint issupported on the at least one balloon, with the two bones remainingseparated from one another by a distance which is greater than thedistance that they are normally separated from one another when thejoint is in a healthy state.

In another preferred form of the invention, there is provided ajoint-spacing balloon catheter comprising:

a shaft having a distal end and a proximal end;

first and second balloons mounted to the distal end of the shaft, thefirst balloon being disposed distal to, and spaced from, the secondballoon, with the portion of the shaft between the first and secondballoons being flexible; and

a handle attached to the proximal end of the shaft.

In another preferred form of the invention, there is provided apparatusfor maintaining space within a joint, the apparatus comprising:

a cannula for providing a corridor to an interior space, the distal endof the cannula comprising a beveled surface; and

a joint-spacing balloon catheter comprising:

-   -   a shaft having a distal end and a proximal end;    -   first and second balloons mounted to the distal end of the        shaft, the first balloon being disposed distal to, and spaced        from, the second balloon, with the portion of the shaft between        the first and second balloons being flexible; and    -   a handle attached to the proximal end of the shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will bemore fully disclosed or rendered obvious by the following detaileddescription of the preferred embodiments of the invention, which is tobe considered together with the accompanying drawings wherein likenumbers refer to like parts, and further wherein:

FIGS. 1A-1D are schematic views showing various aspects of hip motion;

FIG. 2 is a schematic view showing the bone structure in the region ofthe hip joints;

FIG. 3 is a schematic anterior view of the femur;

FIG. 4 is a schematic posterior view of the top end of the femur;

FIG. 5 is a schematic view of the pelvis;

FIGS. 6-12 are schematic views showing the bone and soft tissuestructure of the hip joint;

FIG. 13 is a schematic view showing cam-type femoroacetabularimpingement (FAI);

FIG. 14 is a schematic view showing pincer-type femoroacetabularimpingement (FAI);

FIG. 15 is a schematic view showing a labral tear;

FIG. 16 is a schematic view showing how a perineal post is used inconjunction with an external traction device to distract the hip jointin a conventional hip distraction;

FIGS. 17-19 are schematic views showing a novel joint-spacing ballooncatheter formed in accordance with the present invention;

FIG. 20 is a schematic flowchart showing one novel aspect of a novelmethod for distracting a joint;

FIG. 21 is a schematic view showing the novel joint-spacing ballooncatheter of FIGS. 17-19 being deployed within a hip joint;

FIG. 22 is a schematic flowchart showing another novel aspect of a novelmethod for distracting a joint;

FIG. 23 is a schematic view showing how the leg of a patient may bemanipulated once the ball of the femur is being supported on theinflated balloon of the joint-spacing balloon catheter, and once theexternal distracting force previously applied to the distal end of theleg has been released;

FIG. 23′ is a schematic view showing a peel-away sheath covering ajoint-spacing balloon catheter formed in accordance with the presentinvention;

FIGS. 23A-23D are schematic views showing an outer guiding member whichmay be used to deploy the joint-spacing balloon catheter within thejoint;

FIGS. 24-28 are schematic views showing how one or more expandableelements may be used to tether the joint-spacing balloon catheter to thecapsule of the joint;

FIG. 28A is a schematic view showing another means for stabilizing thejoint-spacing balloon catheter within a joint;

FIGS. 29 and 30 are schematic views showing how additional lumens may beprovided in the elongated shaft of the joint-spacing balloon catheter inorder to accommodate additional structures, e.g., guidewires,obturators, working instruments, optical fibers, etc.;

FIGS. 31-35 are schematic views showing alternative configurations forthe balloon of the joint-spacing balloon catheter;

FIGS. 36-38 are schematic views showing additional alternativeconfigurations for the balloon of the joint-spacing balloon catheter;

FIGS. 39-52 are schematic views showing that the joint-spacing ballooncatheter may comprise multiple balloons, with those multiple balloonsbeing arranged in a variety of configurations;

FIGS. 53-55 are schematic views showing how a balloon of thejoint-spacing balloon catheter may comprise a plurality of separatechambers, with those chambers being arranged in a variety ofconfigurations;

FIGS. 56-60 and 60A-60D are schematic views showing how a balloon of thejoint-spacing balloon catheter may incorporate puncture protectionwithin its structure;

FIGS. 61-63 are schematic views showing how a associated structure maybe used in conjunction with the joint-spacing balloon catheter so as toprovide puncture protection for a balloon of the joint-spacing ballooncatheter;

FIGS. 64-72 are schematic views showing how a supplemental structure maybe provided within a balloon of the joint-spacing balloon catheter so asto provide fail-safe support in the event that the balloon should loseits integrity;

FIGS. 73-78 are schematic views showing additional mechanisms forexpanding a balloon of the joint-spacing balloon catheter;

FIGS. 79 and 80 are schematic views showing an inflatable perineal postprovided in accordance with the present invention;

FIGS. 81 and 82 are schematic views showing another inflatable perinealpost provided in accordance with the present invention;

FIGS. 83-90 are schematic views showing how a joint-spacing ballooncatheter may be placed in the peripheral compartment of the hip joint aswell as in the central compartment of the hip joint;

FIGS. 91-99 are schematic views showing a preferred construction for thejoint-spacing balloon catheter of the present invention;

FIGS. 100 and 101 are schematic views showing means for folding aballoon of the joint-spacing balloon catheter and withdrawal of thejoint-spacing balloon catheter from a joint through a beveled cannula;

FIGS. 102-104 are schematic views showing how the joint-spacing ballooncatheter is used to provide a counterforce to the force returning theball of the femur to the acetabular cup when external distraction isreduced;

FIG. 105 is a schematic view showing the access portals commonly used inarthroscopic hip surgery;

FIGS. 106-112 are schematic views showing various ways in which theballoons of the joint-spacing balloon catheter may be disposed within ahip joint;

FIGS. 113-115 are schematic views showing additional ways in which theballoons of the joint-spacing balloon catheter may be disposed within ahip joint;

FIG. 116 is a schematic view showing abduction of the leg prior torelease of the external traction;

FIG. 117 is a schematic view showing intra-procedure deflation of theballoons of the joint-spacing balloon catheter in order to evaluateprogress of the therapy;

FIGS. 118 and 119 are schematic views showing a rigid/flexible shaftcoupling in the proximal portion of the shaft to enable the handle to beselectively moved out of the way; and

FIGS. 120 and 121 are schematic views showing a construction in whichthe distance between the two balloons is variable.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Novel Joint-SpacingBalloon Catheter

In one form of the present invention, there is provided a noveljoint-spacing balloon catheter for use in distracting a joint, and moreparticularly for maintaining the distraction of a previously-distractedjoint, as will hereinafter be discussed in detail.

More particularly, in this form of the invention, and looking next atFIGS. 17-19, there is shown a novel joint-spacing balloon catheter 5formed in accordance with the present invention. Novel joint-spacingballoon catheter 5 generally comprises an elongated shaft 10 having aballoon 15 disposed at its distal end and a handle 20 disposed at itsproximal end. If desired, and as will hereinafter be discussed, multipleballoons 15 may be disposed on the distal end of elongated shaft 10.

Elongated shaft 10 is preferably flexible, and preferably includes aninternal stiffener 25 extending along at least a portion of its lengthso as to facilitate proper positioning of balloon 15 during use.Internal stiffener 25 may comprise a round or rectangular wire (e.g.,such as is shown in FIG. 19), and may be made out of a metal (e.g.,stainless steel, Nitinol, etc.) or a polymer. If internal stiffener 25comprises a rectangular wire, the short axis (of the cross-section) ofthe wire can provide flexibility (e.g., to enable the distal end of thejoint-spacing balloon catheter 5 to navigate around the curvature of thefemoral head), whereas the long axis (of the cross-section) of the wirecan provide stiffness to better control the position of the balloon inthe joint space. If desired, elongated shaft 10 may also include asubstantially rigid overshaft 30 adjacent to handle 20 so as to furtherstiffen the proximal end of elongated shaft 10, whereby to providebetter control for the positioning of balloon 15. Rigid overshaft 30 canbe a stainless steel tube, a hard polymer tube, etc. Rigid overshaft 30may be about 10 cm to about 30 cm in length, but is preferably about12.5 cm to about 22.5 cm in length. A steering cable 35 is provided forsteering the direction of the distal end of shaft 10, whereby to steerthe direction of balloon 15. More particularly, steering cable 35 (FIG.19) extends through elongated shaft 10 between the distal end ofelongated shaft 10 and a steering control mechanism 40 provided onhandle 20. By manipulating steering control mechanism 40, the user isable to steer the direction of the distal end of shaft 10, and hence thedirection of balloon 15, e.g., in the manner shown in FIG. 18. Moreparticularly, steering control mechanism 40 and steering cable 35 areadapted to cause shaft 10 to bend, preferably in the manner of an arc,which can facilitate positioning of balloon 15 in a joint, e.g., in thecentral compartment of the hip joint, behind the ball of the femur. Thisarc can be a radius of about 5 mm to about 10 cm, but is preferably aradius of about 1 cm to about 5 cm. Steering cable 35 may be stainlesssteel, and may further comprise a low friction coating (e.g.,polytetrafluoroethylene (PTFE)) so as to reduce friction and/or wear.Alternatively, steering cable 35 may slide in a low friction lumen(e.g., in a PTFE tube).

Balloon 15 is preferably selectively inflatable/deflatable via aninflation/deflation lumen 45 (FIG. 19) extending through elongated shaft10 and handle 20. An inflation/deflation control mechanism 50 isinterposed between inflation/deflation lumen 45 and a supply port 55which is connected to an appropriate fluid reservoir (not shown). Bymanipulating inflation/deflation control mechanism 50, the user is ableto inflate/deflate balloon 15 as desired. Inflation/deflation controlmechanism 50 may comprise a stopcock, a valve, a pump and/or other fluidcontrol mechanisms. Balloon 15 preferably includes an atraumatic tip 60at its distal end.

Inflation/deflation control mechanism 50 may comprise a valve whichcontrols flow to and from balloon 15. By way of example but notlimitation, the valve may be a simple open/close type of valve. Ifjoint-spacing balloon catheter 5 comprises two or more balloons (seebelow), and if each balloon can be independently inflated/deflated, theinflation/deflation control mechanism 50 may comprise a multipleposition valve. By way of example but not limitation, where thejoint-spacing balloon catheter comprises two balloons 15, and whereinflation/deflation control mechanism 50 comprises a multiple positionvalve, in a first position, the valve closes flow to both balloons; in asecond position, the valve opens flow to the first balloon but closesflow to the second balloon; in a third position, the valve opens flow tothe second balloon but closes flow to the first balloon; and in a fourthposition, the valve opens flow to both balloons. Alternatively,inflation/deflation control mechanism 50 may regulate the amount offluid in a balloon 15 (i.e., adding fluid to, or withdrawing fluid from,balloon 15 so that balloon 15 contains a pre-determined quantity offluid) and/or regulate the pressure of the fluid in a balloon 15 (i.e.,increasing or decreasing the pressure of the fluid in balloon 15 so thatthe fluid in the balloon has a pre-determined pressure).

On account of the foregoing, joint-spacing balloon catheter 5 may haveits balloon 15 set to its deflated state via inflation/deflation controlmechanism 50, the deflated balloon may be advanced to a remote siteusing handle 20 and steering control mechanism 40, and thenjoint-spacing balloon catheter 5 may have its balloon set to itsinflated state by further manipulating inflation/deflation controlmechanism 50, whereby to enable balloon 15 to support tissue andmaintain the distraction of a previously-distracted joint, as willhereinafter be discussed in detail.

Novel Method for Distracting a Joint

In another form of the present invention, there is provided a novelmethod for distracting a joint, preferably the hip joint, and preferablyusing novel joint-spacing balloon catheter 5.

More particularly, in this form of the invention, and looking now atFIG. 20, the hip joint is first distracted using a standard legdistraction technique, e.g., by positioning a perineal post between thepatient's legs, applying an external distraction device to the distalend of the leg and using the external distraction device to pull on thedistal end of the leg with a substantial force, and then adducting theleg so as to unseat the ball of the femur from the acetabular cup, inthe manner described above and shown in FIG. 16. This action separatesthe head of the femur from the acetabular cup by a distance which isgreater than the distance that they are normally separated from oneanother when the joint is in a healthy state, whereby to distract thejoint and create a substantial intrajoint space. By way of example butnot limitation, the head of the femur may be separated from theacetabular cup by a distance of approximately 10-20 mm or more, andpreferably in the range of approximately 15 mm.

Next, joint-spacing balloon catheter 5, with its balloon 15 set in itsdeflated state, is inserted into the space created between the ball ofthe femur and the acetabular cup. This may be done under directvisualization (i.e., using an endoscope inserted into the distractedjoint), or under fluoroscopy, or both.

Then balloon 15 is inflated. See FIG. 21.

Next, the distal force which was previously applied to the distal end ofthe leg is partially or fully released. Release of the full distractionforce has the beneficial effect of completely eliminating the tensionload imposed on the intervening tissue of the leg, whereas a partialrelease of the distraction force only partially eliminates the tensionload imposed on the intervening tissue of the leg—however, even suchpartial release of the distraction force can still meaningfully reducethe tension load imposed on the intervening tissue of the leg, and itprovides a safeguard in the event that balloon 15 should prematurelydeflate, e.g., mid-procedure. The aforementioned partial or full releaseof the external distraction force allows the ball of the femur to seatitself on the inflated balloon, with the balloon acting as a spacer soas to maintain a desired spacing between the ball of the femur and theacetabular cup. This action keeps the head of the femur separated fromthe acetabular cup by a distance which is greater than the distance thatthey are normally separated from one another when the joint is in ahealthy state, whereby to maintain a substantial intrajoint space whichprovides the surgeon with excellent access to the central compartment ofthe hip joint. By way of example but not limitation, the head of thefemur may be maintained separated from the acetabular cup by a distanceof approximately 10-20 mm or more, and preferably in the range ofapproximately 15 mm. Thus, joint distraction is maintained even though asubstantial distraction force is no longer being applied to the distalend of the leg with an external distraction device. Since jointdistraction can be reliably maintained without the risk of damage to theintervening tissue from a substantial externally-applied distractionforce, the traditional concern to complete procedures in 90 minutes orless is substantially diminished, and complications from jointdistraction are greatly reduced. This is a very significant improvementover the prior art.

With respect to the foregoing method of the present invention, it shouldalso be appreciated that once the joint-spacing balloon catheter 5 issupporting the load of the femoral head (i.e., maintaining the spacebetween the femoral head and acetabular cup), the balloon can be furtherinflated or deflated so as to increase or decrease the space between thefemoral head and acetabular cup.

With the joint so distracted, the arthroscopic surgery can then proceedin the normal fashion. Among other things, this includes accessing thecentral compartment with instruments, performing therapy on the labrum,treating femoroacetabular impingement, treating articular cartilagewithin the central compartment of the hip joint, etc.

Significantly, and in accordance with another novel aspect of thepresent invention (see FIG. 22), the use of joint-spacing ballooncatheter 5 can enable the leg to be manipulated while the joint is in adistracted state. More particularly, it has been discovered that, onceballoon 15 has been inflated within the joint and the pulling forceapplied to the distal end of the leg by an external distraction devicehas been partially or fully released, so that the head of the femur isresting on the balloon, the leg can be moved about (i.e., pivoted) onthe balloon. Manipulation can include flexion and extension, adductionand abduction, as well as internal and external rotation. See, forexample, FIG. 23. This manipulation of the leg while the joint is in adistracted, balloon-supported state enables more of the joint anatomyand pathology to be visualized and accessed, for superior surgicalresults. By contrast, a patient's leg cannot be manipulated in thismanner when the leg is being distracted in a conventional manner, i.e.,by a pulling force applied to the distal end of the leg by an externaldistraction device. Therefore, procedures can be performed using thepresent invention which cannot be performed using conventionaldistraction techniques. This is a very significant improvement over theprior art.

Additionally, some procedures which would normally require the creationof an additional portal to access pathology can be accomplished withoutthe creation of the additional portal, thereby reducing the visible scarand potential morbidity of the additional portal. This is also asignificant improvement over the prior art.

At the conclusion of the arthroscopic surgery, a distal force isre-applied to the distal end of the leg (e.g., via the externaldistraction device) so as to take the load off the inflated balloon, theballoon is deflated, and then the joint-spacing balloon catheter isremoved from the interior of the joint. Alternatively, the balloon maybe deflated and removed from the joint without the re-application of adistal force to the leg by an external distraction device.

Finally, the distal force applied to the distal end of the leg isreleased, so as to allow the ball of the femur to re-seat itself in itsnormal position within the acetabular cup.

With respect to the foregoing method of the present invention, it shouldbe appreciated that joint-spacing balloon catheter 5 can be specificallylocated in the joint space so as to preferentially bias the position ofthe femoral head relative to the acetabulum when the pulling force onthe distal end of the leg is relaxed and the ball of the femur transfersits load to (i.e., is seated on) the inflated balloon. For example,positioning joint-spacing balloon catheter 5 so that balloon 15 is moreposterior in the joint causes the femoral head to settle in a moreanterior position, which can improve visualization and access to theposterior acetabular rim.

With respect to the foregoing method of the present invention, it shouldalso be appreciated that joint-spacing balloon catheter 5 can be placedin the joint space so as to provide better visualization and access tothe peripheral compartment of the hip.

Thus it will be seen that the present invention provides a safe andsimple way to significantly reduce trauma to intervening tissue in theleg when practicing leg distraction, since a substantialdistally-directed force only needs to be applied to the distal end ofthe patient's leg long enough for the deflated balloon to be positionedin the distracted joint and for the balloon to thereafter beinflated—the distally-directed distraction force does not need to bemaintained on the distal end of the patient's leg during the surgeryitself. As a result, trauma to the intervening tissue is greatlyreduced, and the surgeon no longer needs to limit the duration ofdistraction to 90 minutes or less in order to avoid damage to theintervening tissue. This is a very significant improvement over theprior art.

In addition, the use of the present invention enables more of the jointanatomy and pathology to be visualized and accessed, since supportingthe ball of the femur on an inflated balloon allows the initial externaldistraction to be relaxed, and allows the leg to be manipulated on theinflated balloon while the joint is in a distracted state. By contrast,the leg cannot be manipulated in this manner while the leg is beingdistracted in a conventional manner, i.e., by a pulling force applied tothe distal end of the leg by an external distraction device. Therefore,arthroscopic procedures can be performed using the present inventionwhich cannot be performed using conventional distraction techniques.This is a very significant improvement over the prior art.

Additionally, some procedures which would normally require the creationof an additional portal to access pathology can be accomplished withoutthe creation of the additional portal, thereby reducing the visible scarand potential morbidity of the additional portal. This is also asignificant improvement over the prior art.

Further Details of the Joint-Spacing Balloon Catheter

It will be appreciated that balloon 15 preferably serves as a both aspacer to allow access to the central compartment of the hip joint andas a pivot support to allow the manipulation of the femur while thejoint is distracted. Balloon 15 is constructed so as to be atraumatic inorder to avoid damaging the anatomy, including the cartilage surfaces ofthe joint. At the same time, and as will hereinafter be discussed infurther detail, balloon 15 may be appropriately textured and/or sculptedin order to help maintain its position within the joint, preferentiallyto enhance engagement with either one of the acetabulum or femur, whilestill allowing the opposing bone to move smoothly over the balloonsurface.

In one preferred form of the invention, elongated shaft 10 has an outerdiameter of about 0.040″ (or less) to about 0.250″ (or more). An outerdiameter of approximately 0.120″ to 0.200″ is preferred for many hipapplications.

If desired, a retractable and/or removable sheath may be provided overshaft 10 in order to cover balloon 15 prior to inflation. This sheathmay be a peel-away design, as is commonly used in vascular cathetersystems. See, for example, FIG. 23′ which shows a peel-away sheath 56covering the distal end of elongated shaft 10 (including covering twoballoons 15 provided on the distal end of the elongated shaft). Apeel-away sheath construction enables the sheath to be removed during orafter delivery of the balloon(s) to the desired site. The retractableand/or removable sheath may comprise a polymer. The polymer may be of alow friction type so as to facilitate smooth advancement of the sheaththrough the anatomy during delivery (e.g., the sheath may be formed outof PTFE or expanded-PTFE or nylon).

And if desired, the distal end of shaft 10 can be pre-shaped with a bendso as to give joint-spacing balloon catheter 5 a directional bias at itsdistal end.

Furthermore, if desired, and looking now at FIGS. 23A-23D, an outerguiding member 57 may be provided for directing joint-spacing ballooncatheter 5 to a location within the joint. More particularly, in thisform of the invention, outer guiding member 57 comprises a central lumen58 sized to slidably receive joint-spacing balloon catheter 5—the outerguiding member is advanced into position within the joint, and thenjoint-spacing balloon catheter 5 is advanced down the central lumen 58of outer guiding member 57 and then out the distal end of outer guidingmember 57 so that the distal end of joint-spacing balloon catheter 5 isproperly disposed within the interior of the joint.

More particularly, FIG. 23A is a schematic view showing an outer guidingmember 57 which may be used to deploy joint-spacing balloon catheter 5within the joint. In many instances, the portal through the skin doesnot directly align with a desired location within the joint space (e.g.,with the acetabular rim region of the hip joint). Outer guiding member57 has a curve at its distal end which can be aligned with the desiredlocation within the joint space, thus facilitating delivery ofjoint-spacing balloon catheter 5 to the desired joint space. Thejoint-spacing balloon catheter 5 is advanced through the central lumen58 of outer guiding member 57 and exits in a direction which betterfacilitates navigating the distal end of the joint-spacing ballooncatheter to the desired joint space, e.g., around the femoral head. Thejoint-spacing balloon catheter 5 may have a pre-shaped distal end thatfurther enables guidance into the joint space. Alternatively,joint-spacing balloon catheter 5 could be steerable as discussed above.In one preferred form of the invention, outer guiding member 57 ispositioned in the patient such that the distal tip of outer guidingmember 57 is at or near the entrance to the central compartment of thehip (FIGS. 23C and 23D). Alternatively, the distal end of outer guidingmember 57 can be placed within the central compartment of the hip. Thedistal tip of outer guiding member 57 is oriented in the desireddirection for proper placement of the balloon. Joint-spacing ballooncatheter 5 is then advanced through the central lumen 58 of outerguiding member 57 and into the joint space until balloon 15 is in thedesired location (the arrows in FIGS. 23C and 23D indicate direction ofballoon catheter delivery). The outer guiding member can be used to helpadjust the final balloon position. The outer guiding member 57 can beleft in place during the procedure to help tether the joint-spacingballoon catheter in position within the joint. Additionally, outerguiding member 57 can provide a conduit to remove the joint-spacingballoon catheter from the body.

In one preferred form of the invention, balloon 15 is preferablyapproximately 28 mm in diameter, although it can also range from about10 mm (or less) in diameter to about 50 mm (or more) in diameter ifdesired. Furthermore, in one preferred form of the invention, the lengthof balloon 15 is preferably approximately 50 mm, although it can alsorange from about 10 mm (or less) in length to about 75 mm (or more) inlength if desired. In this respect, it will be appreciated that balloonsof various sizes may be used to address patients of different sizes,variations in anatomy, and/or different pathologies.

Balloon 15 may be inflated with a pressure of up to about 1000 psi, andis preferably inflated with a pressure of up to about 200 psi, and ismost preferably inflated with a pressure of up to about 100 psi. In thisrespect it will be appreciated that it is generally accepted that aforce of about 50-80 lbs. is sufficient to distract the hip joint. Inorder for joint-spacing balloon catheter 5 to support this force, itmust provide sufficient pressure over a sufficient surface area(force=pressure×area). Although a number of different balloon sizes andoperating pressures can be envisioned, there are limitations on theballoon size and pressure to consider. On the one hand, the balloon mustbe large enough to cover a sufficient amount of cartilage such that thepressure on the cartilage is lower than that which would damage thecartilage. On the other hand, the balloon must be small enough so as topermit access to, and visualization of, the operative areas. Hence,there is an optimal range of balloon size and operating pressure, andthis optimal range is dependent on tissue dynamics.

In one preferred form of the invention, balloon 15 is fabricated so asto be semi-compliant, although it can also be fabricated so as to becompliant or non-compliant if desired. Examples of semi-compliantballoon materials include polyurethane, nylon and polyether block amide(PEBAX). An example of a compliant balloon material is silicone rubber.An example of a non-compliant balloon material is polyethyleneteraphthalate (PET). A compliant or semi-compliant balloon is generallypreferred over a non-compliant balloon since it will deform under loadto the shape of the surface which the balloon is contacting in order tohelp distribute load onto that surface. A semi-compliant balloon isgenerally most preferred since it will retain some aspects of itspre-load shape even when under load, which can be helpful in directingor maintaining bone positioning, particularly when the leg is beingmanipulated while in a distracted state. The thickness of the balloonmaterial is preferably in the range of about 0.001″ to about 0.020″, andis most preferably between about 0.002″ and about 0.012″. The durometerof the balloon material is preferably in the range of about 30 Shore Ato about 85 Shore D, and is most preferably between about 40 Shore D andabout 85 Shore D.

If desired, the surfaces of balloon 15 can be textured (e.g., withdimples, ridges, etc.) or covered with another material (e.g., a coatingor covering) so as to prevent slippage of the balloon along cartilagewhen the balloon is being used to support a joint. At the same time,this surface texture or non-slip covering is configured so as to engagethe cartilage without causing cartilage damage. In one preferred form ofthe invention, only a portion of the outer surface of the balloon istextured or covered with a non-slip material. For example, the portionof the balloon which faces the acetabulum may be textured or coveredwith a non-slip material, but the portion of the balloon which faces thefemoral head may be non-textured or non-covered, so as to keep thesurface facing the acetabulum from slipping while allowing the surfacefacing the femoral head to slide relative to the femoral head. Inanother preferred form of the invention, a majority of the balloonsurface is textured or covered with a non-slip material. In yet anotherpreferred form of the invention, two or more different textures ornon-slip coverings are provided on the outer surface of the balloon,e.g., depending on the particular cartilage surface which they areintended to engage.

In yet another embodiment of the invention, the balloon is covered witha low friction material which enables slippage of a joint surface on theballoon. The low friction material may cover some or all of the balloonsurface.

The balloon may comprise both low slippage and low friction coverings ifdesired.

Furthermore, if desired, fluoroscopic markings can be incorporated intoor disposed on elongated shaft 10, or incorporated into or disposed onballoon 15, or incorporated into or disposed on another part ofjoint-spacing balloon catheter 5, so as to render the apparatus visibleunder X-ray. Such fluoroscopic markings may comprise radiopaque inkapplied to the apparatus, radiopaque bands applied to the apparatus,radiopaque material incorporated in the construction of the apparatus,and/or a radiopaque fluid used to inflate the balloon (such as acontrast agent). By way of example but not limitation, a radiopaque bandmaterial could comprise platinum. By way of further example but notlimitation, a radiopaque fluid could comprise a contrast agent such asDodecafluoropentane.

In one preferred form of the invention, balloon 15 is preferablyinflated with a liquid medium, e.g., saline; however, it could also beinflated with a gaseous medium, e.g., air. Among other things, theballoon can be inflated with a high viscosity fluid.

This latter construction may be beneficial in the event of a balloonpuncture as it would slow the pace of balloon deflation. If desired, afluid could be used which changes viscosity when subject to changes intemperature, electrical charge, magnetic field, or other means.Alternatively, the balloon can be filled with a compound which increasesin viscosity when exposed to saline. This latter construction can beadvantageous in certain circumstances, e.g., in the event of a balloonpuncture, the escaping fluid would react with the saline present in thejoint and could at least partially seal the puncture hole in theballoon.

Where balloon 15 is inflated with a gaseous medium, and that gaseousmedium is air, inflation/deflation control mechanism 50 may comprise apump, and supply port 55 may be open to the atmosphere.

Where balloon 15 is inflated with a liquid medium, the joint-spacingballoon catheter 5 may further comprise an inflation mechanism (notshown in FIGS. 17 and 18, but shown as an inflation syringe in FIG. 91).The inflation mechanism can be a syringe, a pump, an indeflator, orother commonly used liquid inflation mechanisms. In general, a simplehand-operated syringe mechanism of the sort shown in FIG. 91 isgenerally preferred. The inflation mechanism may separately connect tothe supply port 55, e.g., via a Luer-type fitting.

The inflation time of the balloon is preferably less than 2 minutes, andmore preferably less than 1 minute, and more preferably less than 30seconds. In one aspect of the invention, and looking now at FIGS. 24-28,joint-spacing balloon catheter 5 further comprises one or moreexpandable elements 60 in addition to balloon 15. These expandableelements 60 can be another balloon, a collapsible braid, and/or someother structure which can expand when desired to a larger lateraldimension. Expandable element 60 can be used to releasably securejoint-spacing balloon catheter 5 to the joint capsule. In oneembodiment, and as shown in FIG. 24, an expandable element 60 is locatedat the distal end of the joint-spacing balloon catheter. This expandableelement 60 is laterally expanded once the distal end of the ballooncatheter (and the expandable element 60) has passed through the capsule62 (FIG. 25) at the far side of the joint, so that the expandableelement is deployed on the far side of the capsule, whereby to stabilizeballoon 15 within the joint. In another embodiment, a second expandableelement 60 is provided proximal to the first expandable element 60 butdistal to balloon 15 (FIG. 26) and is expanded adjacent to the internalsurface of the far capsule so that the far side of the capsule issandwiched between the two expandable elements 60, whereby to furtherstabilize balloon 15 within the joint. In this respect it should beappreciated that the two expandable elements 60 may or may not beexpanded simultaneously. In yet another embodiment, and looking now atFIG. 27, one or more expandable elements 60 are disposed proximal to theballoon 15, to tether the joint-spacing balloon catheter to capsule 62at the proximal portion of the joint, such as is shown in FIG. 28.

In another embodiment (FIG. 28A), a second cannula 63 is used to securethe distal end of joint-spacing balloon catheter 5 relative to theanatomy. More particularly, in this form of the invention, the distaltip of joint-spacing balloon catheter 5, (or a flexible element 64 whichextends from the distal end of the joint-spacing balloon catheter, e.g.,a guidewire) is passed into the second cannula 63. The flexible elementcould be a wire, a suture, a ribbon, a catheter, a braid, or some otherconstruction which is flexible or semi-flexible. The flexible element 64can be received within the second cannula and/or, if desired, grippedwithin the second cannula. A gripping feature (not shown) could beprovided in the second cannula to achieve this result.

Alternatively, the flexible element 64 could pass entirely through thesecond cannula, e.g., in the manner shown in FIG. 28A. In any case, thisconstruction results in the tip of joint-spacing balloon catheter 5being partially (e.g., laterally) or fully (e.g., laterally andlongitudinally) stabilized in position by the second cannula 63.

Additionally, and looking now at FIG. 29, another lumen 65 can beprovided in elongated shaft 10 to accommodate a guidewire, obturator,light fiber, electrical wire, or the like, or as an additional inflationlumen, etc. And, as shown in FIG. 30, further lumen(s) 70 can beprovided for working instruments, etc. If desired, a pre-shapedguidewire or obturator can be placed through one of the lumens ofelongated shaft 10 in order to bias the tip direction of thejoint-spacing balloon catheter 5 as the joint-spacing balloon catheteris advanced over the pre-shaped guidewire or obturator. Alternatively, asecond steerable wire (not shown) can be placed through one of thelumens, so as to enable steering of the balloon catheter in a seconddirection.

To improve resistance to kinking, or to provide the shaft with thedesired stiffness and torsional characteristics, a braid or coil 71(FIG. 30) may be incorporated into the catheter. The braid or coil couldcomprise a stainless steel wire, a Nitinol wire, etc. Braid or coil 71may be incorporated in any section of joint-spacing balloon catheter 5,but is preferably located in at least the flexible section of thecatheter.

In FIGS. 17 and 18, balloon 15 is shown with a generally cylindricalconfiguration. However, if desired, balloon 15 can have differentconfigurations. Thus, for example, and looking now at FIGS. 31 and 32,balloon 15 can comprise a pair of opposing flat surfaces 72; or, andlooking now at FIGS. 33 and 34, balloon 15 can have an hourglass shapewhich includes an intermediate section 73 of reduced diameter; or, andlooking now at FIG. 35, balloon 15 can have a generally hourglass shapewith a pair of opposing flat surfaces 72. The aforementioned hourglassshapes, although depicted symmetrical, can also be asymmetric. Forexample, one end of the hourglass-shaped balloon may be of a largerdimension (length, diameter, etc.) than the other end of thehourglass-shaped balloon.

Balloon 15 may also be in the form of an arc or other curvature (i.e., ageometry where one side has a greater curvature than the other side), orsome other shape (e.g., U-shaped), so as to fit around the ligamentumteres. See FIG. 36. Additionally, balloon 15 could have the shape of atorus, so as to provide a seat for the ball of the femur. See FIGS. 37and 38.

It is also possible to provide joint-spacing balloon catheter 5 withmore than one balloon 15. Where more than one balloon is provided, theballoons can be disposed in series (i.e., end-to-end, such as is shownin FIG. 39), or in parallel (such as shown in FIGS. 40 and 41), with orwithout complementary geometries (such as shown in FIGS. 42 and 43), orcombinations of such geometries (such as shown in FIG. 44), or toroidal(such as is shown in FIG. 45), etc. The shafts of the multiple balloonsmay be separated at their distal end (such as is shown in FIG. 40) ormay be joined at their distal ends (such as is shown in FIG. 41). Themultiple balloons may be of the same construction, or they may be ofdifferent constructions. For example, the multiple balloons may be ofdifferent sizes, shapes, materials, compliances, coatings, surfacetextures, coverings, colors, and/or other aspects of construction.Additionally, the multiple balloons may be inflated to differentpressures and/or volumes.

These multiple balloons 15 can also be disposed in a mutually-supportingconfiguration, such as is shown in FIGS. 46-52. By arranging themultiple balloons 15 in a mutually-supporting configuration, themultiple balloons 15 may better conform to the acetabulum and femoralsurfaces, which can be beneficial in order to reduce the pressure on thecartilage and/or to help maintain the balloons in position within thejoint space (i.e., to prevent slipping). In this form of the invention,a balloon catheter 5 could have an assembly of balloons 15 that wouldcollectively act as a compliant or semi-compliant device even though theindividual balloons are themselves non-compliant, or vice versa. Anadditional benefit of arranging the multiple balloons 15 in amutually-supporting configuration is that if one of the balloonsdeflates, the other balloons can still maintain a substantial portion ofthe joint space. In one preferred construction, the balloons 15 canslide against each other so as to spread out, e.g., so as to spread outin a lateral direction.

Where joint-spacing balloon catheter 5 comprises multiple balloons 15,preferably, a separate inflation/deflation lumen is provided for eachballoon, so that each balloon can be separately inflated or deflated toa desired degree and/or at a desired time, although a singleinflation/deflation lumen could be used to simultaneouslyinflate/deflate more than one balloon. By permitting each balloon of agroup of balloons to be selectively inflated, the surgeon can influencethe manner in which the ball of the femur is supported relative to theacetabular cup. In one preferred manner of use, each of the balloons maybe inflated to a different volume (and/or pressure) than others of theballoons. This approach can be used to impart a specific shape to theoverall balloon structure, whereby to influence the manner in whichdistraction is maintained. Also, some of the balloons 15 can be madecompliant, and others of the balloons can be made non-compliant, so asto achieve a desired pressure distribution and/or shape for the overallballoon structure.

It is also possible to provide each of the balloons 15 with a pluralityof separate internal chambers 75 (FIGS. 53-55). Preferably each of theseseparate chambers 75 can be selectively inflated so as to influence themanner in which the ball of the femur is supported relative to theacetabular cup. Thus, in this sort of construction, selective inflationof the various chambers can be used to adjust the position of the ballof the femur within the acetabular cup when the external distractionforce applied to the distal end of the leg is relaxed. The use ofmultiple chambers may also provide a safer design. More particularly, inthe event that one of the chambers 75 is punctured during a procedure,the use of multiple chambers 75 may permit some joint distraction to bemaintained, thus reducing the chances that, for example, an instrumentwill be wedged between the femoral head and acetabulum.

If desired, balloons 15 can be formed so as to be puncture resistant inorder to minimize the possibility of inadvertently deflating theballoon, e.g., with an errant surgical instrument. To this end, andlooking now at FIG. 56-59, a balloon 15 can embed, or sandwich, apuncture-resistant structure 80 (e.g., a coil or mesh or strand or braidformed out of Nitinol, or stainless steel, or a polymer, etc.) betweentwo layers of material (preferably a non-abrasive elastomer).Alternatively, the puncture-resistant structure 80 could be placed onone side of, or embedded within, a single sheet of material, such as isshown in FIG. 60. This puncture-resistant structure 80 may be a separateelement added to the outer wall of the balloon or a coating applied tothe outer wall of the balloon. The puncture-resistant structure 80 mayalso be a layer of material within the side wall of the balloon; forexample, the outer layer may be a puncture-resilient material (such aspolyurethane) to enhance puncture resistance, while the inner layermaterial (e.g., PET) maintains the balloon pressure. In one preferredconstruction, puncture-resistant structure 80 covers a substantialportion of the balloon surface. In another preferred construction, thepuncture-resistant structure 80 covers a smaller portion of the balloonsurface; in this instance, the surface incorporating thepuncture-resistant structure 80 is disposed on the side of the balloonwhere instruments (which could puncture the balloon) are used.

Furthermore, if desired, and looking now at FIGS. 60A-60D, the distalend of joint-spacing balloon catheter 5 could include a shroud 82disposed over balloon 15. Shroud 82 may be formed out of apuncture-resistant material so as to protect balloon 15 from inadvertentpuncture. Additionally, and/or alternatively, shroud 82 could be formedso as to define the volume created within the joint when balloon 15 isinflated. This construction can be advantageous where balloon 15 isformed out of a compliant material and it is desired to control themanner in which space is created within the joint, i.e., by using anon-compliant or semi-compliant shroud 82. Additionally, and/oralternatively, shroud 82 could be formed out of a material whichprovides slippage (e.g., it can be formed out of PTFE or ePTFE). Thiscan be beneficial in a number of ways. First, it can facilitate easierdelivery of the balloon into the joint, including passage through theentry cannula. In a similar way, shroud 82 can also facilitate easierremoval of the joint-spacing balloon catheter from the joint, includingthrough the entry cannula. By having enhanced slippage properties,shroud 82 can also facilitate joint manipulation on the balloon. Theshroud's geometry (e.g., tapered ends) can also facilitate delivery ofthe joint-spacing balloon catheter into, and removal of thejoint-spacing balloon catheter from, the joint space. This may beparticularly beneficial if the balloon catheter goes through an entrycannula.

Alternatively, the shroud 82 could be formed out of a material whichprevents slippage on the joint surface (e.g., a low durometerelastomer). This can be beneficial to enable the balloon to remainstationary on the joint surfaces once it has been placed in the jointspace. Additionally, and/or alternatively, shroud 82 can be constructedso as to provide better endoscopic visualization of the balloon; forexample, shroud 82 can be an opaque color.

Alternatively, and looking now at FIGS. 61-63, a shield 85 could beplaced alongside balloon 15 so as to protect the balloon from beingpunctured from that direction. Shield 85 is preferably introduced intothe joint after the balloon has been inserted and inflated, but shield85 could also be inserted into the joint prior to that if desired.Shield 85 could be made out of a material similar to thepuncture-resistant structure 80 described above.

Alternatively, and looking now at FIGS. 64-68, aballoon-within-a-balloon configuration can be used to provide one ormore secondary “fail-safe” (or “safety”) balloons 90 within the primaryballoon 15—such a construction can minimize the risk that complete jointdistraction will be lost in the event that the primary balloon 15 isinadvertently deflated, e.g., by an accidental puncture. If desired, theinner balloon 90 can be made of a different material than the outerballoon 15. In one preferred construction, inner balloon 90 isnon-compliant and outer balloon 15 is semi-compliant. The inner andouter balloons 90, 15 (respectively) could also have different wallthicknesses, geometries, or other aspects of construction as discussedabove.

Alternatively, a different type of secondary structure can be deployedin balloon 15 in order to prevent balloon 15 from completely collapsingin the event that the balloon is punctured. In one embodiment, andlooking now at FIG. 69, a wire 95 is delivered into the interior of theballoon and fills up a portion of the internal balloon volume; in theevent that the balloon is punctured, wire 95 provides support to preventthe joint space from completely collapsing. Wire 95 is preferably madeof Nitinol, but could also be formed out of another metal or polymer ifdesired. In another embodiment, and looking now at FIG. 70, a wire 100is delivered across the length of the balloon and set in a bowedconfiguration. The bowed wire 100 provides mechanical support in theevent that the balloon is punctured. In FIG. 71, an exemplary mechanicalscaffold 105 is shown deployed in the interior of the balloon so as toprovide a safety mechanical support. In FIG. 72, an expandable foam 110is deployed within the interior of the balloon; foam 110 expands to fillsome or most of the internal balloon space. In one embodiment,expandable foam 110 absorbs fluid and will therefore absorb saline whichmakes its way into the balloon, e.g., in the event of a balloonpuncture. This construction can reduce the speed with which a puncturedballoon will deflate.

In yet another embodiment (FIGS. 73 and 74), the balloon is filled withbeads 115. Beads 115 may be an absorbent polymer or foam, ornon-absorbent. As shown in FIGS. 75-77, if beads 115 are non-absorbent,the balloon's inflation fluid can be evacuated from the balloon afterbeads 115 have been introduced into the inflated balloon, leaving acompact “bean bag” structure to maintain the joint space. As shown inFIG. 78, beads 115 may be delivered into the interior of the balloon ina strand configuration, i.e., mounted on a filament 116. This approachhas the additional advantage that, in the event that the balloon shouldlose its integrity, beads 115 can be safely removed without leaving anybeads in the hip joint, i.e., by pulling proximally on filament 116. Ifdesired, beads 115 can be disposed between a primary outer balloon 15and secondary inner balloon 90.

If desired, joint-spacing balloon catheter 5 can include pressureregulation, e.g., a relief valve (not shown) to ensure that a balloon isnot inflated beyond a maximum level, or an alarm or other alert (notshown) to advise the user that a balloon has been inflated beyond apre-determined level. This can be important to avoid damage to thepatient's tissue or to reduce the risk of inadvertent balloon rupture.

Furthermore, a check valve (not shown) may be installed on the inflationport(s) 55 to enable joint-spacing balloon catheter 15 to bedisconnected from the fluid reservoir while maintaining pressure inballoon 15.

It is also possible to place markings (e.g., longitudinal lines) alongthe body of balloon 15, or to color the balloon material, so as toimprove endoscopic visualization of the balloon, including to show thedegree of balloon inflation. Alternatively, the fluid used to inflatethe balloon may be colored, or the balloon surface may have texture, inorder to aid visualization of the balloon. Alternatively, a transparent,thick-walled balloon 15 can be used to increase visualization of theballoon by increasing the refraction of light, which will make theballoon foggy in appearance. Alternatively, a coating may be applied tothe balloon in order to improve the endoscopic visualization of theballoon.

Alternatively, a second balloon or an expandable extrusion could beplaced over the primary balloon so as to improve endoscopicvisualization. The second balloon and/or expandable extrusion may becolored for improving endoscopic visualization. This configuration canalso add to the puncture resistance of the primary balloon and assist inthe delivery and retrieval of the primary balloon.

The joint-spacing balloon catheter 5 may also comprise a sensor (notshown). The sensor can measure the temperature of the surrounding tissueor fluid in the joint (e.g., the sensor may be a temperature sensor).The sensor may also detect characteristics of the adjacent cartilage,such as thickness, density, and/or quality (e.g., the sensor may be anultrasound device, etc.). The sensor could be located on shaft 10 or onballoon 15, or on another portion of joint-spacing balloon catheter 5.

External Distraction of the Leg

In the foregoing description, the external distraction of the leg isgenerally discussed in the context of applying a distally-directeddistraction force to the distal end of the leg. However, it should beappreciated that the distally-directed distraction force may be appliedto another portion of the leg, e.g., to an intermediate portion of theleg, such as at or about the knee. Thus, as used herein, the term“distal end of the leg” is meant to include substantially any portion ofthe leg which is distal to the ball of the femur, such that by applyingthe external distraction force to the leg, a tension load is imposed onthe intervening tissue. Furthermore, as used herein, the term“intervening tissue” is intended to mean the tissue which is interposedbetween the location where the external distraction force is applied tothe leg and the ball of the femur.

Inflatable Perineal Post

The present invention also preferably comprises the provision and use ofa novel inflatable perineal post for facilitating joint distraction.

More particularly, and looking now at FIGS. 79 and 80, there is shown aninflatable perineal post 120 which generally comprises a relativelynarrow, substantially rigid inner core 125 surrounded by a relativelywide, substantially soft inflatable balloon 130. In an alternativeembodiment, and looking now at FIGS. 81 and 82, inflatable perineal post120 comprises a soft inflatable balloon 130 which is supported on one ormore sides by a substantially rigid support structure 135. Such anon-cylindrical construction, with inflation being directed alongselected directions, can be highly beneficial, since it can reduceengagement of the non-working portions of the perineal post with patientanatomy (e.g., the genitalia). Still other post shapes andconfigurations will be apparent to one skilled in the art in view of thepresent disclosure.

The inflatable balloon 130 of the inflatable perineal post 120 ispreferably constructed out of a semi-compliant material, but it may alsobe compliant or non-compliant. The inflatable balloon 130 of theinflatable perineal post 120 may involve a covering (not shown) forcontact with the patient; this covering may be formed out of a non-slipmaterial. The inflatable balloon 130 is preferably inflated with anappropriate fluid (e.g., air) using a manual or electric pump. Theinflatable perineal post 120 could include a read-out panel displayingthe balloon pressure.

The inflatable perineal post 120 may also comprise physiologic sensors(not shown) for monitoring parameters such as patient skin temperatureand blood flow. Such parameters may be reflective of patient conditionsof interest to the surgeon, e.g., a falling patient skin temperature isfrequently indicative of reduced blood flow. These physiologic sensorsmay be incorporated into the surface of the inflatable balloon 130, orthey could be separate sensors which are included as part of a kitprovided with the inflatable perineal post. The physiologic sensors areadapted to be connected to a monitor so as to provide read-outs on themonitor.

In use, the inflatable perineal post 120 is positioned (in a deflatedcondition) between the patient's legs, the joint is distracted bypulling on the distal end of the leg so that the ball of the femur isspaced from the acetabular cup, the balloon 130 is inflated, ajoint-spacing balloon catheter 5 is inserted into the distracted joint,the balloon 15 is inflated, the force applied to the distal end of theleg is relaxed so that the ball of the femur settles back down onto theone or more inflated balloons 15, and then the perineal post balloon 130is at least partially deflated. At this point the arthroscopic surgerycan be conducted without trauma to the patient's tissue, due to eitherthe distal distraction of the leg or due to engagement of the perinealpost with the tissue of the patient. At the conclusion of the surgery,the distal end of the leg is pulled distally again, the perineal postballoon 130 is inflated, the joint-spacing balloon 15 is deflated, thejoint-spacing balloon catheter 5 is removed from the joint, and thejoint is reduced. Alternatively, the balloon 130 could be inflated priorto pulling on the distal end of the leg. Or, alternatively, the perinealpost balloon 130 could be deflated prior to withdrawal of the forcebeing applied to the distal end of the leg. In some cases, only one ofeither (i) pulling on the leg, or (ii) inflating of the perineal post isperformed in order to remove or re-position the joint-spacing balloon15.

If desired the inflatable perineal post 120 may be used to replace astandard perineal post, and is used in conjunction with a standardtraction table; in other words, in this form of the invention, theinflatable perineal post 120 is not used in conjunction with ajoint-spacing balloon catheter 5.

One Preferred Form of the Invention

In one preferred form of the present invention, the aforementioned novelmethod for distracting the joint is implemented using the aforementionednovel joint-spacing balloon catheter 5 and the aforementioned inflatableperineal post 120.

More particularly, in this form of the invention, the hip joint is firstdistracted by pulling on the distal end of the leg just above the ankle,and then inflating the inflatable perineal post, where the perineal postis positioned between the patient's legs. The leg may be adducted so asto lever the femur laterally. Alternatively, the inflatable perinealpost could be inflated prior to the distal end of the leg being pulleddistally. In any case, this action separates the head of the femur fromthe acetabular cup by a distance which is greater than the distance thatthey are normally separated from one another when the joint is in ahealthy state, whereby to distract the joint and create a substantialintrajoint space. By way of example but not limitation, the head of thefemur may be separated from the acetabular cup by a distance ofapproximately 10-20 mm or more, and preferably in the range ofapproximately 15 mm.

Next, the surgeon identifies a portal location for delivery ofjoint-spacing balloon catheter 5. Then a stylet-filled needle is placedinto the joint, the stylet is removed, a guidewire is delivered throughthe needle, and then the needle is removed. The guidewire can be placedso that it extends along the desired delivery path for the joint-spacingballoon catheter 5, whereby to facilitate proper deployment of thejoint-spacing balloon catheter.

An arthroscopic cannula or outer guiding member may then be emplaced ifdesired; in this instance, the guidewire may be removed if desired.

Next, a joint-spacing balloon catheter 5 of the appropriate size isselected from a kit providing a range of differently-sized joint-spacingballoon catheters. Then the joint-spacing balloon catheter 5 isdelivered over the guidewire (either percutaneously or through acannula) to the target site between the femoral head and the acetabulum.The joint-spacing balloon catheter 5 may be rotated as appropriate ifthere is asymmetry in the balloon's shape. Alternatively, thejoint-spacing balloon catheter 5 may be delivered through a cannulawithout the use of a guidewire.

Next, a syringe (or other inflation device) is secured to thejoint-spacing balloon catheter 5, and the balloon 15 is inflated to thedesired pressure and/or size. Balloon 15 may be inflated to a size andpressure such that when external distraction is reduced, the space inthe joint remains substantially unchanged. Alternatively, balloon 15 maybe inflated to a size and pressure such that when external distractionis reduced, the space in the joint is reduced by a small amount as thehead of the femur settles back down on the balloon. In any case, thisaction keeps the head of the femur separated from the acetabular cup bya distance which is greater than the distance that they are normallyseparated from one another when the joint is in a healthy state, wherebyto maintain a substantial intrajoint space which provides the surgeonwith excellent access to the central compartment of the hip joint. Byway of example but not limitation, the head of the femur may bemaintained separated from the acetabular cup by a distance ofapproximately 10-20 mm or more, and preferably in the range ofapproximately 15 mm. The balloon 15 is preferably inflated to a pressureof less than 100 psi, and more preferably inflated to a pressure ofapproximately 30-75 psi. If there is more than one balloon 15, theadditional balloon(s) 15 can be inflated. If the additional balloon(s)15 are used to affect the direction of joint spacing, the pressureand/or size of each balloon 15 is adjusted so as to achieve the desiredjoint spacing direction.

Once the balloon(s) 15 have been inflated to the desired pressure and/orsize, the distraction force applied to the leg is at least partiallyremoved, allowing the head of the femur to rest on the inflatedballoon(s) (which is/are itself/themselves supported by the acetabulum).

Additionally, the inflatable perineal post 120 is deflated asappropriate; this may occur before the external distraction force on theleg is released.

The balloon(s) 15 can be re-positioned by re-applying distraction forceto the leg and/or re-inflating the inflatable perineal post 120,deflating balloon(s) 15 and re-positioning the joint-spacing ballooncatheter 5, re-inflating the balloon(s) of the joint-spacing ballooncatheter, then releasing the leg distraction and/or deflating theinflatable perineal post. The balloon(s) 15 may be placed in a locationwhich directs the distraction in a preferred direction. Alternatively,where the joint-spacing balloon catheter comprises a plurality ofballoons, the balloons may be inflated to different sizes and/orpressures in order to direct the joint distraction in a preferreddirection.

With the balloon(s) maintaining the joint distraction, the leg may bemanipulated (i.e. rotated, flexed, etc.) in order to visualize andaccess pathology through the established portals.

Then the arthroscopic surgery is conducted. The leg may be manipulated anumber of times through the procedure in order to visualize, access andtreat various pathologies.

At the conclusion of the arthroscopic surgery, the hip joint isdistracted again, e.g., by pulling on the distal end of the leg justabove the ankle, so as to lift the head of the femur off the balloon(s).The perineal post balloon may be inflated. The balloon(s) 15 of thejoint-spacing balloon catheter is/are deflated and the joint-spacingballoon catheter is removed. Thereafter, the external distraction forceapplied to the leg may be removed, allowing the head of the femur tosettle back on the acetabulum.

In another form of the invention, while the distal end of the leg isheld stationary, the perineal post 120 is inflated to break the suctionseal of the hip joint and enable the joint-spacing balloon catheter 5 tobe placed in the joint and inflated. In this case, no pulling on the legis performed. This would have the benefit of eliminating a piece ofequipment from the surgery and reducing the corresponding surgical timeassociated with using that equipment.

Peripheral Spacer Balloon

In yet another form of the invention, and looking now at FIGS. 83-87,the joint-spacing balloon catheter 5 can be used to perform some or allof the joint distraction. In one embodiment, a first joint-spacingballoon catheter 5 is placed adjacent to the femoral head (e.g., in theperipheral compartment) and the balloon is inflated (FIG. 83). The legis then manipulated in abduction or adduction (FIG. 84), depending onballoon location, thus levering the femoral neck against the balloon.This levering action opens the central compartment (i.e., the spacebetween the femoral head and the acetabulum) and creates a gap at theacetabular rim. A second joint-spacing balloon catheter 5 is theninserted into the gap (FIG. 85) and delivered into the centralcompartment of the joint (i.e., the space between the femoral head andthe acetabulum). In one preferred form of the invention, this secondjoint-spacing balloon catheter comprises two balloons 15 disposed in aserial configuration. The balloons of the second joint-spacing ballooncatheter 5 are then inflated (FIG. 86) to distract the joint; that is,to open up the joint space. In one embodiment, the balloon of the firstjoint-spacing balloon catheter 5 is placed on the lateral/superioraspect of the femoral neck. Once the balloons of the secondjoint-spacing balloon catheter 5 have been inflated, the balloon of thefirst joint-spacing balloon catheter 5 can be deflated and withdrawn(FIG. 87). The balloon of the first joint-spacing balloon catheter 5 maybe of a different size and shape than the balloons of the secondjoint-spacing balloon catheter 5. It also may be inflated to a differentpressure.

Use of Multiple Joint-Spacing Balloon Catheters

In one preferred form of the invention, multiple joint-spacing ballooncatheters 5 are simultaneously used within the joint so as to achievethe desired distraction maintenance. More particularly, in one preferredmanner of use, and looking now at FIG. 88, one joint-spacing ballooncatheter 5 is disposed so that its balloon(s) 15 are disposed in thecentral compartment (for ease of illustration, only one balloon 15 isshown in the central compartment in FIG. 88), and one joint-spacingballoon catheter 5 is disposed in the peripheral compartment (for easeof illustration, only one balloon 15 is shown in the peripheralcompartment in FIG. 88). As a result, when the external distraction isreleased, the balloon(s) 15 in the peripheral compartment will cooperatewith the balloon(s) 15 in the central compartment so as to providedistraction maintenance with minimal lateralization of the femoral headrelative to the acetabulum. More particularly, when distractionmaintenance is provided using balloon(s) 15 in only the centralcompartment (FIG. 89), the femoral head may try to move superiorly andlaterally when the external distraction is released, which can inhibitthe surgeon's view of the central compartment. But if balloon(s) 15 areerected in the peripheral compartment (e.g., against the femoral neck)as well as in the central compartment (e.g., in the manner shown in FIG.88), the femoral head will try to move downwardly and medially when theexternal distraction is released due to the presence of the balloons inthe peripheral compartment, whereby to push the femoral head below theballoon(s) in the central compartment and avoid lateralization. See FIG.90. Avoidance of such lateralization provides a more stable distractionmaintenance.

Although balloon(s) 15 have been described here as being used to avoidlateralization of the femoral head, they can also be used to move thefemoral head in a preferential direction relative to the acetabular cup.For example, if the surgeon has a anteriorly/medially located pincerimpingement, it may be desirable to move the femoral head more posteriorto increase surgical access. By placing and inflating balloon(s) 15 inthe anterior region of the femoral neck, the femoral head can be movedmore posterior, thus creating more space to access and treat the pincerimpingement pathology. There may also be situations where balloons 15are placed elsewhere in the joint to preferentially shift the locationof the femoral head.

In an alternative embodiment, the balloon in the peripheral compartmentis deflated but remains in position to be used at a later point in theprocedure. For example, when the surgeon desires to operate in theperipheral compartment, the surgeon can re-inflate the balloon locatedin the peripheral compartment. This will push the capsule away from thefemoral neck, thus creating operative space.

Kits

The joint-spacing balloon catheter 5 and the inflatable perineal post120 may be offered as part of a single kit. A guidewire or obturator,outer guiding member, beveled cannula and a balloon inflation device mayadditionally be provided.

Preferred Construction in General

Looking next at FIG. 91, there is shown a joint-spacing balloon catheter200 which comprises one preferred form of the present invention.Joint-spacing balloon catheter 200 generally comprises an elongatedshaft 205 having a distal end 210 and a proximal end 215.

Distal end 210 of elongated shaft 205 comprises an atraumatic tip 220.In one preferred form of the present invention, and looking now at FIG.94, atraumatic tip 220 comprises a silicone cap 225. Silicone cap 225 isconstructed so as to have a very soft durometer, so that inadvertentengagement of atraumatic tip 220 with tissue (e.g., articular cartilage,labrum, etc.) will minimize any trauma to the tissue. Silicone cap 225is preferably made of an elastomer (e.g., silicone rubber). Silicone cap225 preferably has a radius of approximately 0.01″ to 0.25″, and morepreferably has a radius of about 0.09″.

Referring again to FIG. 91, the proximal end of shaft 205 is secured toa handle 230. Handle 230 preferably comprises a grip 235 and aspring-return trigger 240, whereby pulling spring-return trigger 240towards grip 235 causes the distal end of elongated shaft 205 toarticulate, e.g., in the manner shown in FIG. 92 or in the manner shownin FIG. 93. In one preferred form of the invention, joint-spacingballoon catheter 200 is intended to be used in the hip, and the distalend of elongated shaft 205 is configured to articulate about a radius ofapproximately 12-38 mm, and more preferably to articulate about a radiusof approximately 25 mm. In this respect it should be appreciated thatcadaver lab testing has shown that an articulation radius of larger thanabout 20-35 mm can result in the distal end of elongated shaft 205colliding with the acetabulum, and an articulation radius of less thanabout 20-35 mm can result in the distal end of elongated shaft 210colliding with the femoral head. The distal tip 220 of joint-spacingballoon catheter 200 is preferably able to articulate at least 90degrees off the longitudinal axis of elongated shaft 205, and morepreferably at least 120 degrees off the longitudinal axis of elongatedshaft 205, and even more preferably about 180 degrees off thelongitudinal axis of elongated shaft 205.

Handle 230 may also be detachable from shaft 205 after the balloons (seebelow) are inflated.

Joint-spacing balloon catheter 200 is preferably configured so as toarticulate in the same plane as that of handle 230, e.g., in the mannershown in FIGS. 92 and 93, since such a construction is similar to otherarticulating surgical instruments commonly used in the field of hiparthroscopy. In addition, such a construction allows the joint-spacingballoon catheter 200 to be used on both right and left hips withoutmodification.

Referring again to FIG. 91, a pair of balloons 245 are disposed adjacentto the distal end of the shaft. Balloons 245 are separated from oneanother by a shaft portion 250. Balloons 245 are inflatable/deflatablevia a fluid fitting 246 provided on handle 230 and one or more lumens(not shown in FIG. 91) running through elongated shaft 205. Balloons 245may be independently inflatable/deflatable or they may beinflatable/deflatable in a coordinated fashion. Preferably balloons 245are constructed so that when the balloons are inflated and not subjectedto any external forces, the balloons have a diameter which is largerthan their length. Preferably, the balloons 245 are 0.39″ to 1.57″ indiameter, and more preferably about 1.10″ in diameter. Preferably, theballoons 245 are 0.39″ to 1.57″ in length, and more preferably about0.80″ in length. Balloons 245 are preferably an ellipsoid shape.Balloons 245 are preferably constructed of Nylon 12 polymer materialwith a Shore D hardness of 79 to 115. Preferably the shaft portion 250separating balloons 245 from one another is flexible. Preferably the gapbetween the two balloons 245 (i.e., the length of shaft portion 250) isapproximately 0.5″ to approximately 1.5″.

Preferred Shaft Construction

Elongated shaft 205 of joint-spacing balloon catheter 200 is preferablyconstructed so as to provide substantial articulation, hightorqueability and excellent column strength, so as to facilitate properplacement of the joint-spacing balloon catheter within the joint. Thisis preferably achieved by utilizing a unique construction for elongatedshaft 205.

More particularly, and looking now at FIGS. 94-99, elongated shaft 205preferably comprises a multi-lumen inner tube 260 which receives anitinol stiffening rod 265 within one of its lumens. Multi-lumen innertube 260 is preferably covered by a kink-resistant braid 270.Kink-resistant braid 270 is preferably covered by a rigid hypotube shaft275 for part of its length. Rigid hypotube shaft 275, and the portion ofkink-resistant braid 270 distal to rigid hypotube shaft 275, arepreferably covered by a flexible polymer layer 280 (FIG. 95). Flexiblepolymer layer 280 is preferably 35 to 72 Shore D durometer, and morepreferably 63 Shore D durometer. A second flexible polymer layer maycover the flexible polymer layer 280 along the shaft portion 250extending between the balloons 245. This second flexible polymer layerhelps contain the kink-resistant braid 270. The second flexible polymerlayer is preferably 35 to 72 Shore D durometer, and more preferably 35Shore D durometer.

Multi-lumen inner tube 260 is preferably formed from a polymer which isconstructed so as to be highly elastic and, together with the remaininglayers of the construction, can take on various shapes without permanentdeformation.

Nitinol stiffening rod 265 is disposed within one of the lumens ofmulti-lumen inner tube 260 and provides stiffening for the multi-lumeninner tube. Nitinol stiffening rod 265 preferably has a variablediameter along its length. More particularly, and looking now at FIGS.94-98, nitinol stiffening rod 265 preferably has a larger diameterproximal end 285 and a smaller diameter distal end 290, with a taperedtransition zone 295 therebetween. The larger diameter proximal end 285has a higher rigidity, which provides the proximal end of elongatedshaft 205 with greater rigidity, whereby to enable transfer of forces tothe distal end of the elongated shaft. The smaller diameter distal end290 provides sufficient rigidity to transfer forces to the distal end ofthe elongated shaft, but it also provides flexibility so that the distalend of the elongated shaft can articulate. The Nitinol stiffening rod265 can also provide sufficient spring action to return the shaft to astraight configuration. The preferred diameter of the distal end 290 ofnitinol stiffening rod 265 is 0.020″, but can preferably range from0.010″ to 0.030″, or from 0.005″ to 0.060″. The tapered section 295,which is preferably located at the transition zone between rigidhypotube shaft 275 and multi-lumen inner tube 260, provides a gradualtransition in rigidity from the rigid hypotube shaft to the flexiblemulti-lumen inner tube. See FIG. 98. This gradual reduction in rigidityis important in achieving the desired curvature when the articulation isactivated. Without this gradual reduction, the shaft may kink at thedistal end of the rigid hypotube shaft 275.

Kink-resistant braid 270 is provided to help distribute the forcescreated in elongated shaft 205 when the elongated shaft is articulated.More particularly, kink-resistant braid 270 allows the mechanicalstresses in the bent shaft to redistribute evenly along the length ofthe elongated shaft rather than concentrate at the weakest point in theshaft. Kink-resistant braid 270 also provides flexibility that not onlyallows elongated shaft 205 to bend but also facilitates the shaftreturning to a non-flexed position. Kink-resistant braid 270 alsotransfers torque from rigid hypotube shaft 275 to distal end 210; thisenables the distal end of the joint-spacing balloon catheter 200 to becontrollably steered during delivery into, and removal from, the joint.Kink-resistant braid 270 is preferably formed so that it can pass fluidstherethrough, as will hereinafter be discussed in further detail.

Rigid hypotube shaft 275 is constructed so as to be substantially rigid,whereby to provide the desired structure for the proximal end of theelongated shaft 205. The rigid hypotube shaft 275 provides both thetransfer of torque and push force from the proximal end of thejoint-spacing balloon catheter 200 to the distal end of thejoint-spacing balloon catheter 200. This provides the surgeon with goodcontrol in positioning the joint-spacing balloon catheter 200.

Flexible polymer layer 280 provides a smooth outer coating for elongatedshaft 205. In one preferred form of the invention, flexible polymerlayer 280 has a durometer which changes over the length of the device.By way of example but not limitation, flexible polymer layer 280 canhave a higher durometer (stiffer) adjacent to the rigid hypotube shaft275 and a lower durometer (softer) adjacent to balloons 245. The softerdurometer enables the distal section to be more flexible, which ispreferably for the articulation of the device.

Since the flexible polymer layer 280, the kink-resistant braid 270, thenitinol stiffening rod 265 and the rigid hypotube shaft 275 areoverlapping structures, their combined mechanical properties result inthe overall flexibility of the system, which increases in flexibilityalong the length of the shaft (FIG. 98).

Preferably, one of the lumens of multi-lumen inner tube 260 is used toinflate/deflate the two balloons 245. To this end, windows 300 (FIGS. 94and 99) are formed in multi-lumen inner tube 260 so as to connect theinflation/deflation lumen to the balloons 245. Significantly,kink-resistant braid 270 overlies these windows 300, interposed betweenthe interior of the inflation/deflation lumen and the interior of theballoon, so that inflation/deflation takes place through thekink-resistant braid itself. By allowing fluid flow through thekink-resistant braid 270 and not removing that portion of the braid, themechanical properties of the braid can be maintained while stillenabling inflation/deflation of balloons 245.

Alternatively, two of the lumens of multi-lumen inner tube 260 may beused to inflate/deflate the two balloons 245. To this end, windows 300(FIGS. 94 and 99) are formed in multi-lumen inner tube 260 so as toconnect a specific inflation/deflation lumen with its correspondingballoon 245.

Cannula

In practice, it has been found that it is generally desirable tofacilitate easy introduction of joint-spacing balloon catheter 200 intothe joint, and easy removal of joint-spacing balloon catheter 200 fromthe joint.

More particularly, and looking now at FIG. 100, joint-spacing ballooncatheter 200 is preferably introduced into a surgical site by passingthe distal end of the balloon catheter through a cannula 310, which isprovided with a beveled distal end 315. Furthermore, balloons 245 arepreferably configured into a reduced-profile condition so as tofacilitate their delivery through the cannula 310. By way of example butnot limitation, FIG. 101 shows a unique 3-step method for foldingballoons 245. In Step 1, the balloon is deflated (e.g., vacuum is pulledfrom the inflation/deflation portal); the balloon is then formed into adiamond-shaped cross-sectional condition. In Step 2, the balloon isfolded from a diamond-shaped cross-sectional condition to apinwheel-shaped cross-sectional condition by rotating the edges of theballoon around the center axis of the balloon shaft. And in Step 3, theballoon is further folded from a pinwheel cross-sectional condition to acollapsed cross-sectional configuration. Once the balloon has beenfolded in the manner shown in FIG. 101, a sheath (e.g., the peel-awaysheath 56 shown in FIG. 23′) may be placed over the folded balloon so asto maintain the balloon in its collapsed cross-sectional configurationuntil the time of use.

As discussed above, cannula 310 comprises a beveled distal end 315 asshown in FIG. 100. The beveled distal end 315 enables the balloon to bemore easily withdrawn back through cannula 310 for removal from thejoint. By way of example but not limitation, the balloon 245 is deflatedprior to removal from the joint. Once deflated, balloon 245 is drawnback through cannula 310; as it is drawn back, the balloon 245 isrotated so that the beveled distal end 315 of cannula 310 collapses andfolds the balloon 245. In this way, the balloon 245 achieves a reducedprofile which enables it to pass through the lumen of cannula 310.

Force Balancing

It will be appreciated that, in order for balloons 245 to maintain spacewithin the joint, it is necessary for balloons 245 to provide acounterforce to the force returning the ball of the femur to theacetabular cup when external traction is relaxed. Thus, when placingballoons 245 in the central compartment, the balloons should be placedso as to provide the desired counterforce to the femur, taking intoaccount the direction of the returning force vector and also thegeometry of the space which is to be maintained. See FIGS. 102 and 103.In this respect it will be appreciated that where the patient's joint isdistracted with the use of external distraction and a perineal post(FIGS. 104 and 17), the returning force vector may be approximately theinverse of the vector V_(D) and so the balloons 245 will be set withinthe joint with this in mind.

Access Portals

In addition to the foregoing, and as noted above, hip arthroscopy iscomplicated by the fact that access to the interior of the hip joint islimited by the location of various bones and neurovascular structures.In practice, only a few locations are available to place the portalsneeded to gain arthroscopic entry into the hip joint. In practice, andas shown in FIG. 105, these are the AL (anterolateral), PL(posterolateral), A (anterior), PALA (proximal anterolateral accessory),MA (mid-anterior), DALA (distal anterolateral accessory) and PTS(peritrochanteric space) portals. In this respect it will be appreciatedthat while each of these portals provides access to the hip joint, theytend to provide only limited access to the hip joint, i.e., the PLportal provides good access to one portion of the hip joint but not toanother portion of the hip joint, etc.

Disposition within the Joint

In one preferred form of the invention, joint-spacing balloon catheter200 is intended to be used in the hip, with balloons 245 and portion 250of shaft 205 (i.e., the portion of the shaft extending between the twoballoons 245) forming a “3-point contact” with the acetabular cup andfemoral head.

More particularly, and looking now at FIG. 106, joint-spacing ballooncatheter 200 is intended to be positioned within theexternally-distracted hip joint, and its balloons 245 thereafterinflated, so that, prior to the external distraction being released,balloons 245 and portion 250 of elongated shaft 205 all sit spaced fromthe ligamentum teres. However, when the external distraction isthereafter released, the femoral head causes joint-spacing ballooncatheter 200 to reconfigure in the manner shown in FIGS. 107 and 108,with distal balloon 245 moving towards the proximal balloon 245, andwith portion 250 of elongated shaft 205 resting against the ligamentumteres, or against the acetabular fossa, or against another portion ofthe acetabular cup, or otherwise disposed in the central compartment, orextending out of the central compartment, etc. In fact, this actionactually occurs in 3 dimensions, with balloons 245 positioningthemselves close to the rim of the concave acetabular cup and portion250 of elongated shaft 205 engaging the ligamentum teres, deeper in thecup. Thus, with the external distraction removed, balloons 245 andportion 250 of elongated shaft 205 form a so-called “3 point contact”with the adjacent hip structures.

This “3-point contact” arrangement has proven to be extremelyadvantageous, since it reliably creates stable distraction maintenancefor a wide range of joint sizes, joint shapes and joint forces. Inaddition, this arrangement is stable when either articular surface ismoved with respect to the other articular surface; for example, movementof the leg while the balloon is maintaining joint distraction. Inaddition, this “3 point contact” arrangement is believed to be equallyapplicable to other joints within the body.

The joint-spacing balloon catheter 200 is preferably positioned alongthe line of the 9 o'clock (posterior) position to the 3 o'clock(anterior) position in the acetabluar cup (where the “12 o'clockposition” is in the superior portion in the acetabular cup). In thisposition, the joint-spacing balloon catheter 200 will have minimalobstruction to the portion of the anatomy which is typically accessedduring femoroacetabular impingement arthroscopic surgery.

FIGS. 106-108 show balloons 245 being set through the PL portal, withthe balloons 245 being disposed in the “10 o'clock” and “2 o'clock”positions.

FIG. 109 shows balloons 245 being set through the A portal, with theballoons 245 being set in the “10 o'clock” and “2 o'clock” positions(the figures show the joint after external distraction has beenreleased).

Thus it will be appreciated that providing a novel joint spacercomprising two balloons 245 connected to one another by a flexible shaft250, provides a highly stable space maintenance structure which is asignificant improvement in the art.

In another embodiment of the invention, an additional step can beperformed during balloon delivery to more optimally place the balloons245 in the joint space. In this embodiment, the distance between theballoons 245 is adjusted using the articulation of the distal end of theshaft; more articulation brings the balloons 245 closer together (asdepicted in FIG. 110). This may be preferable, for example, when closerproximity of the balloons 245 to each other results in better stabilityof the femoral head (once external traction has been removed and thefemoral head is resting on the balloons 245). Articulation of theballoons 245 for purposes of controlling their spacing to each other (asopposed to guiding the joint-spacing balloon catheter 200 into the jointas described above) would typically be performed after balloons 245 havebeen placed into the joint space but prior to inflation of the balloons245. The operation sequence would be as follows: (1) joint-spacingballoon catheter 5, with balloon 15 set in its deflated state, isinserted into the space created between the ball of the femur and theacetabular cup (articulation of the distal end of the shaft can be usedto facilitate guiding the device into the joint space); (2) the distalend of the shaft is rotated to orient the articulation in a differentplane; (3) the distal end of the shaft is articulated to bring theballoons closer together; (4) the balloons are then inflated; and (5)the distal force which was previously applied to the leg is partially orfully released.

FIG. 110 shows balloons 245 being set through the PL portal with theballoons being set in the “10 o'clock” and “2 o'clock” positions, butwith the shaft being bent prior to release of the external traction soas to get the balloons closer to each other.

FIG. 111 shows balloons 245 being set through the PL portal, with theballoons being set in the so-called “fossa” and “1 o'clock” positions,but with the shaft being bent prior to release of the external traction.

FIG. 112 shows balloons 245 being set through the PL portal, with theballoons being set in the “1 o'clock” and “fossa” positions, but withthe shaft being bent prior to release of the external traction.

Among other things, when joint-spacing balloon catheter 200 is used witha patient in a lateral decubitus position (FIG. 113), the forces actingon the balloons after the external distraction has been released assistin creating stable distraction maintenance with excellent access to thelabrum. More particularly, in this situation, gravity will force thefemur downwardly and balloons 245 will force the femur distally, awayfrom the labrum, in the manner shown in FIG. 114 (which is ananterior-posterior view of joint). Correspondingly, when joint-spacingballoon catheter 200 is used during a supine approach, the forces actingon the balloons after the external distraction has been released lessreliably assist in creating stable distraction maintenance. Moreparticularly, gravity will force the femur downwardly, and balloons 245will force the femur distally, away from the labrum, in the manner shownin FIG. 115 (which is a lateral view of joint).

In another preferred form of the invention, and looking now at FIG. 116,the patient's leg may be moved in abduction prior to releasing theexternal traction. This approach helps orient the femur so that itsettles more securely onto the balloons 245 disposed in the acetabularcup when external distraction is released. It has been shown that thiscan more reliably assist in creating stable distraction maintenance witha patient situated in the supine position. Abducting the leg alsodisplaces the leg off the perineal post which may partially or fullyrelieve any lateral force which the post may be placing on the leg andthus the femoral head (which could push the femoral head in a lateraldirection and thereby reduce access to the labrum).

Visibility Under X-Ray

While it is anticipated that joint-spacing balloon catheter 200 willnormally be set under direct visualization from an arthroscope, it isalso desirable that the joint-spacing balloon catheter be visible underX-ray, since this will allow the user to confirm proper catheterplacement before balloon inflation, and also confirm proper balloonseating as the external distraction is released. This is preferablyachieved by forming some or all of elongated shaft 205 out of a materialwhich is at least somewhat X-ray opaque. For example, the shaft 205could comprise a plastic material filled with BaSO₄ (barium sulfate). Inaddition, some or all of one or both balloons 245 may also be formed outof a material which is at least somewhat X-ray opaque. By way of examplebut not limitation, a platinum O-ring (not shown) may be incorporatedunder the proximal end of the proximal balloon 245.

Method of Using Adjustable Balloon Inflation

It should be appreciated that balloons 245 do not need to remaincompletely inflated at all times during the surgery. For example,balloons 245 could be initially fully inflated prior to releasing theexternal distraction, and they could thereafter have their inflationadjusted so that they are thereafter only partially inflated, or theycould be entirely deflated. This could be beneficial if, for example,the surgeon is performing labral refixation and wants to assess how wellthe labrum forms a suction seal with the femoral head. In this example,the surgeon would partially or fully deflate the balloons 245 (FIG. 117)so as to reduce or completely eliminate joint distraction. Moreparticularly, by partial or full deflation of the balloons 245, thefemoral head would settle back into the acetabular cup, enabling thesurgeon to assess the repair and plan and/or perform additionalrefixation if necessary.

As has been disclosed, once the balloons 245 are inflated and externaltraction is released, the femur/leg can pivot on the balloons 245. Thisallows the surgeon to re-position the leg while maintaining distraction,something that is not possible with external traction because thepatient's leg is secured to the traction table. In this respect itshould be appreciated that the femoral head can also freely rotate on apartially or fully deflated balloons 245. This could be useful, forexample, in diagnosing and treating femoroacetabular impingement (FAI).For example, if the surgeon is performing pincer decompression, with thejoint-spacing balloon catheter 200 maintaining the joint space, thesurgeon may want to assess whether further decompression is needed. Bypartially or fully deflating the balloons, the femoral head settles backinto the acetabular cup. By then rotating the leg (for example, flexingand internally rotating), the surgeon can assess whether sufficient bonehas been removed. The balloon can then be re-inflated to continue thedecompression or other central compartment treatment.

Flexible/Rigid Shaft

FIGS. 118 and 119 show another catheter construction. In this form ofthe invention, the proximal portion of elongated shaft 205 includes aflexible section 300 over which slides a rigid collar 305. When therigid collar 305 is moved proximally away from the flexible section 300,the shaft can bend at the location of the flexible tube, however, whenrigid collar 305 is set to span flexible section 300, elongated shaft205 is rigid. A flexible/rigid shaft of the aforementioned sort can behighly advantageous in hip arthroscopy, since it enables the catheter tobe in a rigid condition during entry into the joint so as to facilitatepassage through intervening tissue, but then converted into a flexiblecondition so that the proximal (i.e., handle) end of the catheter can bemoved out of the way during the surgery itself. By way of example butnot limitation, in one form of the invention, the catheter is firstrendered rigid and the distal end of the catheter is introduced into thejoint; then the catheter is rendered flexible and the proximal end ofthe catheter is laid on the surgical drape adjacent to the portal sothat the proximal end of the catheter is out of the way during surgery.

In one preferred form of the invention, the distance between the twoballoons 245 is fixed. This distance is preferably 0.01″ to 1.50″, andmore preferably 0.30″ to 0.65″. In another preferred form of theinvention (FIGS. 120, 121), the portion 250 of elongated shaft 205 whichis disposed between balloons 245 can vary in length. Such an arrangementcan be extremely helpful in facilitating optimal placement of balloons245 within the joint. For example, a larger joint size may requiregreater spacing between the two balloons 245. Other examples ofsituations where it may be desirable to adjust the spacing betweenballoons 245 may include anatomical variations of the joint likeprotrusio, profunda, etc. By way of example but not limitation, in oneform of the invention, portion 250 of elongated shaft 205 isexpandable/collapsible in the manner of a bellows (see FIGS. 120, 121),and in another form of the invention, portion 250 of elongated shaft 205is telescoping in the manner of two concentric tubes, etc. Preferably alever or plunger or other mechanism 255 (FIG. 120) is provided on handle230 to permit the user to adjust the length of portion 250, whereby toset the spacing between balloons 245. Alternatively, the length ofportion 250 can be self-adjusting once inside the joint, as balloons 245and elongated shaft 205 are subjected to anatomical forces within thejoint. In one such exemplary construction, portion 250 can comprise aspring-like element.

Use of the Present Invention for Other Applications

It should be appreciated that the present invention may be used fordistracting the hip joint in an open, more invasive procedure. Thepresent invention can also be used in hip joint pathologies where jointdistraction is not needed but space creation is needed, e.g., tovisualize and/or to address pathologies in the peripheral compartment orpathologies in the peritrochanteric space. Additionally, the presentinvention may be used for distracting joints other than the hip joint(e.g., it may be used to distract the shoulder joint).

Modifications of the Preferred Embodiments

It should be understood that many additional changes in the details,materials, steps and arrangements of parts, which have been hereindescribed and illustrated in order to explain the nature of the presentinvention, may be made by those skilled in the art while still remainingwithin the principles and scope of the invention.

1.-30. (canceled)
 31. A method for creating space in a joint of a limb,the method comprising: applying force to the limb at a location remotefrom the joint so as to fully distract the joint and create anintrajoint space; while the joint is fully distracted by the forceapplied to the limb at a location remote from the joint so as to createthe intrajoint space, inserting an expandable member into the intrajointspace, the expandable member being inserted into the intrajoint spacewhile the expandable member is in a contracted condition; while thejoint is fully distracted by the force applied to the limb at a locationremote from the joint so as to create the intrajoint space, expandingthe expandable member within the intrajoint space; and reducing theforce applied to the limb at a location remote from the joint so thatthe joint is maintained in a distracted condition by the expandablemember.
 32. A perineal post comprising a balloon.
 33. A perineal postaccording to claim 32 wherein the balloon is disposed over asubstantially rigid core.
 34. A perineal post according to claim 33wherein the substantially rigid core has a circular cross-section.